I pretty much agree with all the pros and cons that have been pointed out about this movie, so I'll just say a few extra words.
Bruce Lee's first real entrance into American pop culture was his role as Kato, the sidekick of the 1960s superhero The Green Hornet. Though he was just a sidekick to the white protagonist, Bruce Lee's appeal actually surpassed that of the guy who played the Green Hornet (does anyone even remember his name?). Enter the Dragon was Bruce Lee's first and only entrance into mainstream American film. Bruce Lee garnered widespread appreciation for martial arts films in the US and set the landscape for people like Jackie Chan and Jet Li to make a living. His portrayal as the physically fit, ass-kicking, cobra-snagging Asian male hero was a welcome change to the puny, hunched-back "Asians" we see in Broken Blossoms. Unfortunately, however, it is hardly this aspect that really stuck with pop culture. Instead it was the hand-waiving, high-pitched squeals that many Americans seem to remember. As many have pointed out, I think those added squeals definitely hurt the film and made it easy to laugh at martial arts. I wonder what would have happened if the sound effects were toned down to a more regular level. Would people have just found another excuse to laugh?
Another problem I think is that Bruce Lee's opponents don't really even come close in terms of skill. Obviously there's an issue of how much of a superhero you want the protagonist to be, but still I think it probably contributed to viewing his character as an alien. In addition, it is possible that adding those extra squeals and making him sound funny contributes to diminishing his threat to white males. Asians are expected to be puny and nerdy, but if they are too good at martial arts, this stereotype serves as an excuse to laugh.